The present invention has to do with modification of a known assembly for shredding waste material and compacting it into a receptacle. Such a system incorporates a machine known as a shredder/compactor. One such machine, preferred in connection with the present invention, is disclosed in U.S. Pat. No. 3,703,970, issued Nov. 28, 1972, to R. R. Benson. The disclosure of the patent is incorporated herein by reference.
The Benson machine has heretofore been manufactured and supplied commercially by the present assignee.
The machine is adapted to shred or break up waste material and to feed the shredded material into a receptacle, usually a large steel box. When the box begins to fill, the machine acts to force-feed even more material into it, thereby compacting the box contents into a dense form.
The shredder/compactor machine in combination with the receptacle means together form the "assembly" referred to above.
The assembly is commonly used, for example, with apartment buildings and restaurants, to shred and compact their commingled waste mixture into steel boxes. The Benson machine is capable of reducing the volume of the waste material by a factor of about 7:1. The filled boxes are periodically emptied into a compactor-type garbage disposal truck. This truck further compacts the waste with a hydraulic ram and then delivers it to a dump site.
It will be noted that, in this prior system, the shredder/compactor is fed a non-sorted mixture comprising articles and waste products formed of different materials.
In recent times, recycling of waste materials has manifested itself in commercial operations. However, each recycler is usually limited by his equipment to processing only one type of waste material.
This fact has obliged the waste handlers supplying the recyclers to sort the waste into distinct lots, each such lot 12 containing only material of a certain type. These lots then have to be separately shipped to different recyclers. In other words, the shredded aluminum cans go to one recycler and the shredded glass to another.
At this point it is appropriate to describe in a general way the Benson shredder/compactor machine. It comprises an elevated, rectangular frame supported at its corners by legs. There is room to insert the receptacle between the legs and beneath the frame. The frame includes a generally rectangular tubular member forming a central, vertical, open-ended throat or passageway. A hopper feeds waste material to the inlet of this passageway. A rotatable, driven, toothed shaft ("rotor") is mounted to one pair of opposed side walls of the tubular member. The rotor thus centrally traverses the passageway adjacent its lower end. The rotor teeth are formed of steel plate and extend outwardly from the shaft in spaced relation along its length. The rotor is capable of high torque, being driven by a motor through reduction gearing. One of the tubular member walls ("the anvil wall"), extending parallel to the rotor, carries an array of spaced-apart anvil members. These anvil members are steel plates, each having a configuration something like that of a ski jump. The anvil members are positioned so that the rotor teeth will mesh with and pass down between them with some clearance. There is also some clearance between the shaft and the anvil members. The turning rotor teeth thus act to trap waste items against the anvil members and slice through them on their downward entry into the anvil gaps. They simultaneously force comminuted material ahead of them through the gap between the shaft and the anvil members and through the gaps between said anvil members. As a result, the shredded bits and pieces are force-fed by the rotor into the receptacle. Projecting from the tubular member wall opposite to the anvil wall is an array of spaced-apart stripper members. These stripper members are also steel plates positioned to mesh with the rotor teeth and having close clearances with said teeth. The stripper members are operative to strip waste material, still clinging to the rotor teeth, as the teeth rotate upwardly therethrough. This stripped material drops into the receptacle.
It needs to be noted that the rotor teeth project downwardly beneath the lower outlet of the tubular member and extend into the mouth of the receptacle, when the teeth are in the lowermost portion of their rotational travel and the receptacle is in close engagement with the underside of the frame. When the receptacle is full, the teeth act to drive the top layer of waste material downwardly and in the direction of rotation, at an angle of about 22.degree. relative to horizontal. As a result, the box contents are compressed and compacted. For this compression to happen, the receptacle necessarily has to rigidly confine the waste materials. Thus there is used a closed box formed of steel plate, said box having a top wall with an opening which corresponds with the outlet of the tubular member. The box, usually mounted on castors, is designed to fit snugly to the undersurface of the frame, thereby providing a seal to effectively prevent the escape of waste material.
The rotor is formed with only two teeth in a vertical plane, said teeth being generally diametrically aligned. Thus there are two "flat" spots on each side of the shaft. The rotor is positioned with its teeth in a horizontal plane to enable the box to be inserted or removed.
The prior system, as described, was characterized by a singular problem when offered to waste handlers supplying recyclers. The heavy steel box was inappropriate as a shipping container to deliver the shredded waste lot to a recycler, who might be located in a different city.